Opal glass compositions

ABSTRACT

Opal glass compositions for producing opal glass articles such as perfume bottles are disclosed. The compositions are borosilicate compositions and further include 0.5-3.0 wt % of CaO and 1.0-6.0 wt % of P 2  O 5 , and the sum of alkaline oxides totals 9-18 wt %.

The invention relates to compositions for opalescent glass, that is,compositions for the production of articles or substrates made ofopalescent glass. Such articles or substrates are obtained in particularfrom compositions inducing the formation of microcrystals distributed intheir thickness, imparting a more or less marked "clouded" and "cottony"appearance.

The perfume and cosmetics industries increasingly are demandingarticles, such as bottles or jars, made of opalescent glass. Theproduction of these articles has in particular the purpose of alteringthe presentation of the products deriving from these industries, inparticular from an aesthetic point of view.

If the invention is not limited to such applications, it nonethelesswill be described in greater detail in reference to the applicationscontemplated by the perfume and/or cosmetics industries, in particularin order to simplify the understanding thereof.

The inventors therefore set themselves the task of defining glasscompositions for the production of articles made of opalescent glass.

Research led the inventors to produce such articles from glasscompositions comprising in particular fluorine, an element capable ofensuring the germination of crystals. This research made it possible toproduce such articles having opalescent, non-opaque walls having asatisfactory light transmission for the contemplated applications. Onthe other hand, aging tests for said articles under storage conditionssimilar to those to which they are intended to be subjected prior tofilling revealed various problems.

To begin with, it was established that storage conditions in a confinedatmosphere, the articles being subjected to fluctuations in temperatureand humidity, lead to the formation of offensive, persistent odors, ofthe vinegar-odor type. The formation of such odors is, of course,completely unacceptable for the applications contemplated by the perfumeand cosmetics industries.

Moreover, the aging conditions tested also disclosed the formation of agreasy gel on the surface of the glass. The formation of such a greasyfilm on the surface requires a washing and/or scouring of the articlesprior to filling. These operations lead to very significant costs and,in addition, must be implemented by the filling industries and not bythe container manufacturers, which also makes this drawbackunacceptable.

During their analysis of the problems which have just been cited, theoriginators of this invention were able to demonstrate the assumedsource of said problems. As a matter of fact, it would appear that theglass compositions used did not have a sufficient hydrolytic resistance.

The purpose of the invention thus is compositions for opalescent glasshaving an improved hydrolytic resistance, considering the resultspresented.

It furthermore is known to produce glass substrates comprising crystalsin their thickness leading to a complete opacity; it involves substratesobtained from compositions of opaline glass. Such compositions aredescribed in particular in patent application WO-96/06052. Thisapplication describes in particular the substitution of phosphorus-basedcompounds in place of fluorine-based compounds, in order to improve thecoefficient of thermal expansion.

The previously set purpose is achieved according to the invention by acomposition for opalescent glass of the borosilicate type including, inaddition, the oxides below within the following limits by weight:

CaO: 0.5-3.0%

P₂ O₅ : 1.0-6.0%

and the sum of the alkaline oxides ranging between 9 and 18%.

The various glass compositions used corresponding to this definition ineffect make it possible to produce articles having in particular asatisfactory hydrolytic resistance for applications such as those ofinterest to the perfume and/or cosmetics industries. As a matter offact, bottles or jars do not have, after a storage under conditions suchas those cited previously, any greasy film or any odor which may bedetrimental to their use or requiring additional cleaning stages priorto filling.

Furthermore, the glass compositions, such as defined, may be melted,then put to use with no problem according to the customary techniquesemployed in the industry for manufacture of bottles and jars intended inparticular for the perfume and cosmetic industries.

The principal and most important component in these glass matrices isSiO₂. The SiO₂ content advantageously ranges between 58 and 72% andpreferably still is in excess of 60% and advantageously less than 66%.On this side of the lower limits, the glass compositions according tothe invention become very problematic to work and the shaping ofarticles becomes almost unrealizable. On the other hand, above the upperlimits, the glass compositions become difficult to melt.

With regard to B₂ O₃ content, it advantageously is in excess of 8% andpreferably in excess of 10% and advantageously does not go beyond 14%and preferably is below 12%. B₂ O₃ acts somewhat in the growth of themicrocrystals which one wishes to obtain. This element also makes itpossible to reduce the viscosity at high temperatures.

The alkalines act on the one hand on the viscosity of the glass and onthe other on the growth of the microcrystals. A low content of alkalineelements leads to high viscosities making melting and shaping of theglass more difficult. On the contrary, overly high contents lead toexcessively low viscosities and in addition disrupt the growth ofmicrocrystals. The alkaline content therefore is advantageously inexcess of 10% and below 15%. These alkaline elements preferably are Na₂O with a content advantageously ranging between 9 and 13% and K₂ O witha content ranging between 1.5 and 2.5%.

In addition to CaO, the compositions advantageously comprise otheralkaline-earth elements such as BaO. These elements, in addition totheir influence on viscosity, contribute essentially to the formation ofmicrocrystals. More particularly, CaO essentially affects the nature ofthe crystals and BaO essentially affects their size. The BaO content byweight thus advantageously ranges between 1 and 4% and preferably is inexcess of 2% and below 3%. With regard to the CaO content, itadvantageously is below 1.5%.

In addition, the glass compositions according to the inventionadvantageously comprise ZnO oxide which also acts in the formation ofmicrocrystals and more particularly on the rate of growth of thesemicrocrystals. The ZnO content thus advantageously is selected below 3%and preferably in excess of 0.5% and preferably still below 1.5%.

The glass compositions according to the invention also advantageouslymay comprise Al₂ O₃ oxide in a content advantageously below 10%. Thisoxide acts in particular on the chemical resistance of the glass as wellas on its viscosity. In addition, low contents are detrimental to thegrowth of microcrystals and reduce chemical resistance. Overly highcontents may lead to excessively high viscosities and a problematicmelting. The Al₂ O₃ content thus advantageously will be in excess of 5%and preferably below 8% and preferably still below 6%.

The glass compositions according to the invention also may compriseother oxides, in particular being capable of acting on the formation ofmicrocrystals. It involves, for example, CeO₂ oxide which promotes inparticular the germination of microcrystals with very low contents, suchas contents below 1000 ppm.

The inventors also were able to demonstrate that the glass compositionsaccording to the invention could comprise a not-negligible fluorinecontent to make up for that of P₂ O₅, still without leading to articleswhich have the cited drawbacks, such as the formation of a greasy filmor the presence of odors after storage. The fluorine content nonethelessadvantageously remains below 1.5% and preferably below 1%.

According to a preferred mode of embodiment of the invention, thecomposition according to the invention comprises the components belowwithin the following weight limits:

    ______________________________________                                               SiO.sub.2                                                                           60-66%                                                                  Na.sub.2 O                                                                           9-13%                                                                  K.sub.2 O                                                                           1.5-2.5%                                                                CaO   0.4-1.5%                                                                Al.sub.2 O.sub.3                                                                    5-6%                                                                    BaO   2-3%                                                                    Ce.sub.2 O                                                                            0-0.1%                                                                B.sub.2 O.sub.3                                                                     10-12%                                                                  ZnO   0.5-1.5%                                                                F     0-1%                                                                    P.sub.2 O.sub.5                                                                     1.5-3%                                                           ______________________________________                                    

Previously it already was stated that the glass compositions thusdescribed according to the invention allow for the production ofarticles having a sufficient hydrolytic resistance; in fact, this glassis comparable to a type 1 glass according to the rules of the Europeanor American Pharmacopeia USP23-NF18. These rules are based onmeasurements of mass hydrolytic resistance, in particular by theover-powder or surface method.

In addition, these compositions for opalescent glass lead to articleshaving an overall light transmission through their wall. This lighttransmission is a function of the microcrystal content in the thicknessof the wall of the article. It preferably is in excess of 10% andadvantageously does not exceed 80%. According to the types ofproduction, that is, according to the types of articles manufactured andtheir intended uses, light transmission in excess of 20%, or even 30% isadvantageous. This light transmission may be expressed in particular inthe form of L or luminance colorimetry, this magnitude being directly afunction of light transmission. This magnitude L is one of thecalorimetric coordinates designated by the letters a, b, L; a and bcharacterizing the chromaticity of the glass and L characterizing theluminance of this same glass, the coordinates in question deriving fromthe trichromatic coordinates X, Y and Z defined and proposed in 1931 bythe Commission Internationale de l'Eclairage (CIE) [InternationalLighting Commission], a commission unanimously recognized as anauthoritative agency in the area of colorimetry. The system ofcoordinates L, a, b commonly called CIELAB, was the subject of anofficial CIE recommendation in 1976 (Commission Internationale del'Eclairage, Colorimetry--Official Recommendations--CIE Publication No.15-2, VIENNA 1986) and is used by a large number of industrial sectors.

The measurement of calorimetric coordinates L, a, b is effected on awall of an article. The measurements of transmission to determine thevalues a, b, L on the wall are carried out with the aid of an InterlabColorquest spectrometer, under illuminant C, 2nd observing.

Concerning the manufacture of articles intended in particular for theperfume and cosmetics industry, the methods used for most of them arethe usual manufacturing methods in the area of manufacture of bottlesand jars. These manufacturing methods are usually automatic: the jarsand bottles are produced, for example, on machines of the IS machinetype.

Nonetheless, for example with respect to the manufacture of perfumebottles, certain articles may be produced in different manners. At thetime of production of a bottle design, it usually is required that thisbottle be produced on different scales. In fact, a perfume line consistsof several forms, which may be, in particular, extracts, perfumes,colognes, toilet waters, samples, display dummies, etc. . . If theperfumes, colognes, toilet waters and samples are produced in largequantity, the same is not true in particular for the extracts and thedisplay dummies. The articles produced in large quantity will beproduced automatically on machines of the type of those citedpreviously. Concerning in particular the extracts and the displaydummies, such production is difficult to plan, in particular for reasonsof costs associated with adaptation of the machines and/or bulkiness ofarticles making the manufacture of these articles incompatible on suchmachines. The methods generally planned for this type of article thenare termed "semiautomatic," that is, the production of these articlescomprises stages involving one or several manual operators.

More particularly for this type of "semiautomatic" production, theinvention provides for glass compositions having a greater working leveland thus being more suited to a manual step at the time of production ofthe articles. In comparison with compositions according to the inventionintended more particularly for an automatic production of articles, suchcompositions advantageously comprise a decreased silica content andincreased alkaline, and more particularly Na₂ O and P₂ O₅ contents. Thevariations in the SiO₂ and Na₂ O contents in particular make it possibleto extend the working level. These variations entail in particular alowering of the melting and refining temperatures. The variation in theP₂ O₅ content essentially offsets the variation in Na₂ O to maintain thedesired rate of microcrystal formation.

Preferably, in comparison with compositions intended more specificallyfor automatic manufacturing, the SiO₂ content is decreased by a valueranging between 3 and 6 expressed in percentage unit and preferablyequal to 5. In the same manner, the alkaline and preferably Na₂ Ocontent is increased by a value ranging between 3 and 6 expressed inpercentage unit and preferably equal to 4.

Likewise again, the P₂ O₅ is increased by a value ranging between 1 and3 expressed in percentage unit and preferably equal to 1.

According to a variant of the invention, the compositions intended moreparticularly for "semiautomatic" manufacturing are characterized by anSiO₂ content ranging between 58 and 63%, an alkaline content rangingbetween 12 and 18%, more particularly with an Na₂ O contentadvantageously ranging between 10 and 13%, and a P₂ O₅ content rangingbetween 2 and 6%.

Preferably, such compositions intended more particularly for"semiautomatic" manufacturing are characterized by an SiO₂ contentranging between 59 and 61%, an alkaline content ranging between 13 and15%, and a P₂ O₅ content ranging between 2.5 and 3%.

A composition for opalescent glass according to the invention, moreparticularly intended for an automatic production, may comprise theoxides below within the following weight limits:

    ______________________________________                                               SiO.sub.2                                                                           65.10%                                                                  Na.sub.2 O                                                                          9.00%                                                                   K.sub.2 O                                                                           2.02%                                                                   CaO   1.05%                                                                   Al.sub.2 O.sub.3                                                                    5.70%                                                                   BaO   2.65%                                                                   Ce.sub.2 O                                                                          0.04%                                                                   B.sub.2 O.sub.3                                                                     11.26%                                                                  ZnO   0.93%                                                                   F     0.45%                                                                   P.sub.2 O.sub.5                                                                     1.80%                                                            ______________________________________                                    

A composition for opalescent glass according to the invention, intendedmore particularly for a "semiautomatic" production, comprising manualstages, may include the oxides below within the following weight limits:

    ______________________________________                                                SiO.sub.2                                                                           60.80%                                                                  Na.sub.2 O                                                                          12.4%                                                                   K.sub.2 O                                                                           2%                                                                      CaO   1.1%                                                                    Al.sub.2 O.sub.3                                                                    5.6%                                                                    BaO   2.7%                                                                    Ce.sub.2 O                                                                           0.04%                                                                  B.sub.2 O.sub.3                                                                     11.2%                                                                   ZnO   0.9%                                                                    F     0.5%                                                                    P.sub.2 O.sub.5                                                                     2.6%                                                            ______________________________________                                    

As was stated previously, the compositions for opalescent glass intendedmore particularly for "semiautomatic" production as well as thecompositions for opalescent glass intended more particularly for"automatic" production have a hydrolytic resistance similar to that of atype-1 glass and therefore satisfactory and a light transmission inexcess of 10%.

Tests have been carried out based on different compositions foropalescent glass according to the invention and are reported in thetable hereinbelow.

The table shows the glass composition for each of the articles producedas well as the L colorimetry through a wall of the articles, the latterhaving been cut beforehand to allow measurement.

    ______________________________________                                                  No 1  No 2      No 3    No 4                                        ______________________________________                                        SiO.sub.2   60,99   60,41     60,44 60,13                                     Na.sub.2 O  12,92   13,21     12,73 12,73                                     K.sub.2 O   2,03    2,01      2,01  2,00                                      CaO         1,05    1,04      1,04  1,03                                      Al.sub.2 O.sub.3                                                                          5,66    5,61      5,61  5,58                                      Fe.sub.2 O.sub.3                                                                          0,03    0,03      0,03  0,03                                      BaO         2,65    2,63      2,63  2,61                                      Ce.sub.2 O  0,04    0,04      0,04  0,04                                      B.sub.2 O.sub.3                                                                           11,22   11,12     11,12 11,06                                     ZnO         0,93    0,92      0,92  0,91                                      F           0,45    0,44      0,44  0,44                                      P.sub.2 O.sub.5                                                                           2,02    2,42      2,74  2,99                                      L Colorimetry                                                                             87,2    66,9      30,6  24,2                                      ______________________________________                                    

To begin with, these tests show that an increase in the P₂ O₅ contentleads to a decrease in light transmission. The light transmissionsobtained from these glass compositions according to the invention arecompletely satisfactory for the contemplated applications.

In addition, the hydrolytic resistance for each of these glass typesalso is satisfactory, in particular for applications such as those ofthe perfume and cosmetics industries.

I claim:
 1. Glass composition which comprises the components belowwithin the following weight limits:

    ______________________________________                                               SiO.sub.2                                                                           60-66%                                                                  Na.sub.2 O                                                                           9-13%                                                                  K.sub.2 O                                                                           1.5-2.5%                                                                CaO   0.5-1.5%                                                                Al.sub.2 O.sub.3                                                                    5-6%                                                                    BaO   2-3%                                                                    Ce.sub.2 O                                                                            0-0.1%                                                                B.sub.2 O.sub.3                                                                     10-12%                                                                  ZnO   0.5-1.5%                                                                F     0-1%                                                                    P.sub.2 O.sub.5                                                                     1.5-3%.                                                          ______________________________________                                    


2. Glass composition according to claim 1, which comprises thecomponents below:

    ______________________________________                                               SiO.sub.2                                                                           65.10%                                                                  Na.sub.2 O                                                                           9.00%.                                                                 K.sub.2 O                                                                           2.02%                                                                   CaO   1.05%                                                                   Al.sub.2 O.sub.3                                                                    5.70%                                                                   BaO   2.65%                                                                   Ce.sub.2 O                                                                          0.04%                                                                   B.sub.2 O.sub.3                                                                     11.26%                                                                  ZnO   0.93%                                                                   F     0.45%                                                                   P.sub.2 O.sub.5                                                                      1.80%.                                                          ______________________________________                                    


3. An opalescent borosilicate glass composition comprising at leastSiO₂, B₂ O₃, CaO, P₂ O₅, and at least one alkali oxide, wherein the SiO₂content ranges between 59 and 61%, the alkali oxide content rangesbetween 13 and 15%, the CaO content ranges between 0.5 and 3%, and theP₂ O₅ content ranges between 2.5 and 3%.
 4. Glass composition accordingto claim 3, which comprises the components below within the followingweight limits:

    ______________________________________                                                SiO.sub.2                                                                           60.80%                                                                  Na.sub.2 O                                                                          12.4%                                                                   K.sub.2 O                                                                           2%                                                                      CaO   1.1%                                                                    Al.sub.2 O.sub.3                                                                    5.6%                                                                    BaO   2.7%                                                                    Ce.sub.2 O                                                                           0.04%                                                                  B.sub.2 O.sub.3                                                                     11.2%                                                                   ZnO   0.9%                                                                    F     0.5%                                                                    P.sub.2 O.sub.5                                                                      2.6%.                                                          ______________________________________                                    


5. A jar or bottle made from the glass composition of claim
 1. 6. A jaror bottle made from the glass composition of claim
 2. 7. A jar or bottlemade from the glass composition of claim
 3. 8. A jar or bottle made fromthe glass composition of claim
 4. 9. The jar or bottle of claim 5,wherein overall light transmission through a wall thereof ranges between10 and 80%.
 10. The jar or bottle of claim 6, wherein overall lighttransmission through a wall thereof ranges between 10 and 80%.
 11. Thejar or bottle of claim 7, wherein overall light transmission through awall thereof ranges between 10 and 80%.
 12. The jar or bottle of claim8, wherein overall light transmission through a wall thereof rangesbetween 10 and 80%.